1. Technical Field
The invention relates to Local Area Networks (LAN). More particularly, the invention relates to the monitoring and control of network packet traffic resulting in the reduction of unnecessary traffic across LANs without the use of bridges or routers.
2. Description of the Prior Art
When LAN networks first started growing in the 1980's, a physical limit was quickly reached due to the LAN cable limitations. To solve this problem, LAN bridges were introduced to tie these physical cables together to form larger networks. The bridge would transparently pass packets between LAN segments. In addition, these bridges also could also eavesdrop on the packets and learn which MAC addresses were on each LAN segment. In this way they could keep unicast traffic on the appropriate LAN segment. This increased the overall network throughput so long as the users set up their topology to keep hosts that frequently talked to each other on the same LAN segment.
At some point however, MAC level broadcasts become an intolerably large percent of the network traffic (when accidental bridge loops occurred at set up, broadcast storms could completely disable a network). Broadcasts not only use up network bandwidth but also use up processing power on every host system that the broadcast is passed to (the processor must analyze every broadcast packet up through the network layer to see if the packet is addressed to it). To solve this problem, routers were introduced to segment the network into separate broadcast domains.
At the router boundary, all broadcasts were intercepted and the router would decide which LANs the broadcast would be propagated on (if any). Routers performed this function by looking into level 3 headers and forced the network to be segmented into network level broadcast domains. Although this solved the problem of excessive broadcasts within the network, it introduced an expensive device that would add latency, limit throughput between these broadcast domains and add complexity to the network. To limit the throughput loss across a router, users were forced into topologies where servers and clients needed to remain within the same broadcast domain.
Switches were introduced to allow the creation of Virtual Local Area Networks (VLAN), allowing users to segment their networks without the high costs of routers or low port count of bridges. The problems associated with switches are typified by U.S. Pat. No. 5,521,913 issued to Gridley on May 28, 1996, which teaches an ethernet switch using cut-through switching. This technique merely forwards packets through the VLAN without examining the packet validity until after the packet has been forwarded. This technique and the current methodologies implemented in ethernet switches do not prevent the occurrence of unnecessary and excessive traffic across the VLAN.
Note: This technique can be applied to either cut through or store and forward switches.
Unnecessary and excessive traffic across the VLAN not only slows down the network but, additionally, requires each end node and computer connected to the network to receive and analyze those packets. The result is the overall loss of network bandwidth. The major cause of this loss is broadcast traffic. The present invention achieves what the prior art does not, that is, reduce the traffic across the VLANs and thereby allow the VLAN bandwidth to be used more efficiently.